MPG for Cummins

[Slow Ride]

Gents, I have a 2007.5 Cummins 6.7L Diesel which has the DPF and EGR deleted along with a 4 inch exhaust and a cold air intake. I have an H&S XRT PRO programmer to run the system and keep it from throwing codes. I recently updated the software from the H&S site and installed the updates. Now I'm getting about 18mpg but I was getting 22mpg (both unloaded). I had the entire system installed because I was constantly at the dealership getting the DPF, Turbo, and or EGR cleaned (about once every 3-6 months). As you can imagine, it was getting expensive. So I opted for the deletes and have had ZERO trouble with the exhaust system since! My issue is that I have no idea what setting to use. The shop that put it together is no longer in business, so there is nobody to ask. Does anyone have an idea which setting is best for MPG. I don't need a race truck. I set the thing to stock and it was horrible. I set it to the next higher level "Tow," and it is better but still not the same. There are two or three higher preset levels plus all kinds of settings for boost, timing, etc. but I'm not a really educated Mech. and I don't want to break anything. Any input for MPG settings would be helpful. Thanks in advance. Dave

 

[LippCJ7]

Re: MPG for Cummins

the most important thing you need to do with diesels is watch the exhaust gas temperature, nothing else really matters, so long as you do not run your Exhaust gasses to hot you will be fine, if you do not have an exhaust gas temperature gauge then get one immediately, with the modifications you have made you absolutely need it, I would also highly suggest you get a tranny temp gauge and a boost gauge although the boost gauge is not as important as the other two.

If your gauge is post turbo keep it below 1250 degrees and you can do what ever you want and you will not hurt your motor, use the setting that fits your driving style best and keeps your EGT's below 1250 degrees, if your pyrometer is preturbo I will need to do some research.

anyway, here is the deal all you are trying to do is keep your turbo from getting to hot and destroying it prematurely, so long as you stay below this temp your motor will do what ever you want, the cummins is an incredibly strong motor that will handle a lot of abuse, a friend always told me to drive it like you stole it, I have a 2000 ford f350 that ran a 13.2 1/4 mile it currently has 350,000 miles on it my dodge doesn't have the mods my ford does but it has 270,000 miles on it and runs great, keep the EGT's controlled and you can do what ever you want and drive it however you want.

 

[agallant80]

Re: MPG for Cummins

You may want to check out the Cummins forum. There are people there that love to tinker with their diesels.
Dodge Cummins Diesel Forum

 

[CharlieB]

Re: MPG for Cummins

Many many moons ago when I tuned the old screaming Detroits I made sure to keep pyros just under 1150 to keep from melting pistons.

 

[ricohman]

Re: MPG for Cummins

My buddy has a 2011 and he was having a similar issue. It turned out to be the programming for the transmission. He figured it was hanging on the gears just a bit longer. He messed around with custom tunes all summer.
But if your mpg is all highway this may not apply.

 

[MTboatguy]

Re: MPG for Cummins

I own two Ford Oil Burners and the least of my worries is the fuel mileage, I worry about the power, if I can afford to own the truck, then I can afford the fuel!

 

[Slow Ride]

Re: MPG for Cummins

I own two Ford Oil Burners and the least of my worries is the fuel mileage, I worry about the power, if I can afford to own the truck, then I can afford the fuel!

Well here is the deal Gents. As it turns out, I was able to get some info. from another source and found that the highest setting "performance" will not only give you another 175hp and nearly 200ft/lbs torque, but also has the best available mpg. I took the time to try all four settings to confirm this information. As I mentioned before, the programmer was installed to prevent the computer from looking for the DPF which was removed because it was a continuous problem. So I figured as long as I have the ability to increase the mileage I should do so! On the "Stock" setting the truck runs at about 17.5-18mpg at 70mph. When adjusted to "Performance" the truck runs at 22.5mpg at 70mph. The settings in between revealed consistent increases in MPG with increases in settings. Admittedly, it will drink like a sailor if I get a heavy foot. PYRO is fine with normal operation. I'm sure I could get it up to a temp that would hurt it if I tried but under normal usage, its a non issue. Being able to "afford the fuel" (MTboatguy) isn't really the issue, but throwing $$ away when I have the ability to stop it seems like a good idea to me. But hey, I'm just a guy with a degree, 20+ years of military service and the owner of 3 trucks with Cummins and one Ford 7.3 over the last couple decades. But by all means, if you enjoy throwing your money away..... knock yourself out.

 

[MTboatguy]

Re: MPG for Cummins

Slow Ride,

If you want to start comparing credentials, then we can do that, I am a West Point Graduate, then retired after 26 years with an O6 rank and I would have made my stars if was not gravely wounded in the first Gulf War and spent the last part of my career in a training capacity, I am a Silver Star recipient, 4 purple hearts and 2 bronze stars, I hold a Masters Degree in Wildlife Biology From Washington State University. Now, If I pissed you off, sir, that is two bad, and I won't apologize for that, but I would say, it does seem as if you took my message incorrectly.

I don't enjoy "throwing" money away, but I also know the cost of having the toys we all play with.

Which Military school did you graduate from? I know you stated 20 years military, but neglected to let me know which institution you attended.

Now, we can keep this pissing match up, or we can simply agree we have a very different idea of things?

The ball is in your court sir.

PS. I still don't worry about the fuel mileage. Just curious, how much did you pay for this system you are trying to tune into your motor?

Another thing I will add, our past life experience really has nothing to do with the topic of fuel mileage and performance of the oil burning trucks.

 

[Slow Ride]

Re: MPG for Cummins

Sir,

I'm an enlisted man and I too have a laundry list of accomplishments. I merely intended to let you know that I'm not new to owning, operating, and maintaining this expensive equipment and I'm not one of the folks who are on here regularly chiming in on conversations which they have no real knowledge of. I appreciate your service and sacrifice to this great nation and I will always yield to your rank....... retired or otherwise. That said, perhaps I did take your comment "incorrectly" but I was looking for tech. advice not a fiscal lesson. I'll agree to disagree on this issue.

 

[MTboatguy]

Re: MPG for Cummins

Then the issue is finished, we will agree to disagree. Thank you for your service as well, I am sure we have both been in and seen situations we wish we could forget.

 

[PETE BUTZEN]

Re: MPG for Cummins

Good Morning ; I am new to this Thread , I have A 1997 Dodge 3500 Cummins , 210,000 mi since new I have never got more than 17 mpg . I forgot to say I have 5 speed manual / 354 gears / dually / flat bead . When truck was New I had pump turned up 17 % . So I was told . This was a factory service . My Friend a 1996 , Same specs He used his Truck for hauling cross country , He had his pump turned up 35% and his mpg empty is 25 at 70 mph . I was told that the factory was not allowing the 35% because of transmission failure any more . Now I know that this was quite some years ago , But I am getting ready to Plan for retirement and I like my truck , We tow our TrophyBoat around a lot . My question is should I have the pump turned up 17 % more ? or is there some thing else I could do ? Thanks Pete .

 

[QC]

Re: MPG for Cummins

OK. I am sorry. I can't handle it. The power has corrupted me and I made a couple of edits in this thread. There is no such thing as a CumminGs. Been in the diesel engine biz my whole life. Pet peeve. :redface:

 

[Vintin]

Re: MPG for Cummins

I've got a 1995 F-700 with the 5.9 Cummins in it if anyone wants to chain rear bumpers together for a ride! :lol: ....and a 96 2500 4x4 with the 5.9.

 

[jbetzelb]

Re: MPG for Cummins

Like the firs response said. Watch your EGT's. H & S have some good tunes for all makes of diesel trucks but if oyu are pushing 200 to 300 horse above stock you will likely hit some high EGT's when your pulling.

 

[Slow Ride]

Re: MPG for Cummins

MTboatguy, I paid a little over $2K for all the mods installed. I realize the fuel issue will take years to pay me back, but like I said, that was not the original intent. I had the mods done because I was at the dealer every few months forking out $500-$700. Since I purchased the truck used, it had no warranty and these "cleanings" were coming out of my pocket.

And I agree, our past accomplishments do not directly impact this conversation other than to say both of us have a history of detail oriented service and education which drives home the point that neither of us are goofballs!

 

[MTboatguy]

Re: MPG for Cummins

Dave,

I just read an article about this in last months diesel magazine, I will have to dig it out and go over it again to see if perhaps I could pass the information along to you to help out on your settings. I know if I run red diesel that we have around here for the farm trucks, I have to clean things a lot more than running our normal street diesel.